带有Windows Mobile 5.0 SDK的WIN32 C程序：使用time_t获取链接器错误'unresolved external'>>

Question

我正在使用Windows Mobile 5.0 SDK为Motorola MC-55A PDA编写WIN32 C程序。我正在尝试获取当前日期和时间。我尝试使用time_t，但收到链接器错误：“函数BasicScanProc中引用了无法解析的外部符号时间”。我没有语法错误。我也尝试过使用ctime函数，struct tm，SYSTEMTIME，但是它们都因上述相同的链接器错误而失败。

我已经检查了头文件，并且上述所有变量，结构和函数（time_t，ctime（）等）都已在该头文件中声明，但是我似乎无法在代码中使用它们。这是我的代码：

#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <string.h>
#include <windows.h>
#include <windowsx.h>

//Variables declaration
time_t current_time;

// Forward declarations
LRESULT CALLBACK BasicScanProc(HWND,UINT,WPARAM,LPARAM);
void    ErrorExit(HWMD, UINT, LPTSTR);
LPTSTR  LoadMsg(UINT, LPTSTR, int);

int WINAPI WinMain(HINSTANCE hInstance,
                   HINSTANCE hPrevInstance,
                   LPWSTR lpszCmdLine,
                   int nCmdShow)
{
    int nResult;

    hInst = hInstance;      // save the instance handle to a global variable
    nResult = DialogBox(hInstance, MAKEINTRESOURCE(IDD_DIALOG_SSCAN), NULL, 
                        BasicScanProc);

    return nResult;
}


LRESULT CALLBACK BasicScanProc(HWND hwnd, UINT uMsg, WPARAM wParam, LPARAM lParam)
{
    DWORD           dwResult;
    TCHAR           szLabelType[256];
    TCHAR           szLen[MAX_PATH];
    TCHAR           szMsgBuf[256];
    LPSCAN_BUFFER   lpScanBuf;
    HWND            hctl_data, hctl_length, hctl_type, hctl1, hctl2, hWndComboBox;

switch(uMsg)
{

case WM_INITDIALOG:

//Below fails with error : 'time_t' : illegal use of this type as an expression  
//C:\Program Files (x86)\Windows Mobile 5.0 SDK R2\PocketPC\include\ARMV4I\stdlib.h : 
//see declaration of 'time_t'

current_time = time(NULL);
printf("Hours since January 1, 1970 = %ld\n", current_time/3600);

//This also fails
//time_t now;
//time(&now);

Windows Mobile 5.0 SDK的time.h的内容如下：-

/***
*time.h - definitions/declarations for time routines
*
*   Copyright (c) 1985-1994, Microsoft Corporation. All rights reserved.
*
*Purpose:
*   This file has declarations of time routines and defines
*   the structure returned by the localtime and gmtime routines and
*   used by asctime.
*   [ANSI/System V]
*
****/

#ifndef _INC_TIME
#define _INC_TIME

#ifdef __cplusplus
extern "C" {
#endif


/* Define _CRTAPI1 (for compatibility with the NT SDK) */

#ifndef _CRTAPI1
#if ( (_MSC_VER >= 800) && (_M_IX86 >= 300) )
#define _CRTAPI1 __cdecl
#else
#define _CRTAPI1
#endif
#endif


/* Define _CRTAPI2 (for compatibility with the NT SDK) */

#ifndef _CRTAPI2
#if ( (_MSC_VER >= 800) && (_M_IX86 >= 300) )
#define _CRTAPI2 __cdecl
#else
#define _CRTAPI2
#endif
#endif


/* Define _CRTIMP */

#ifndef _CRTIMP
#ifdef  _NTSDK
/* definition compatible with NT SDK */
#define _CRTIMP
#else   /* ndef _NTSDK */
/* current definition */
#ifdef  _DLL
#define _CRTIMP __declspec(dllimport)
#else   /* ndef _DLL */
#define _CRTIMP
#endif  /* _DLL */
#endif  /* _NTSDK */
#endif  /* _CRTIMP */


/* Define __cdecl for non-Microsoft compilers */

#if ( !defined(_MSC_VER) && !defined(__cdecl) )
#define __cdecl
#endif

#ifndef _WCHAR_T_DEFINED
typedef unsigned short wchar_t;
#define _WCHAR_T_DEFINED
#endif

/* Define the implementation defined time type */

#ifndef _TIME_T_DEFINED
typedef long time_t;        /* time value */
#define _TIME_T_DEFINED     /* avoid multiple def's of time_t */
#endif

#ifndef _CLOCK_T_DEFINED
typedef long clock_t;
#define _CLOCK_T_DEFINED
#endif

#ifndef _SIZE_T_DEFINED
typedef unsigned int size_t;
#define _SIZE_T_DEFINED
#endif


/* Define NULL pointer value */

#ifndef NULL
#ifdef __cplusplus
#define NULL    0
#else
#define NULL    ((void *)0)
#endif
#endif


#ifndef _TM_DEFINED
struct tm {
    int tm_sec; /* seconds after the minute - [0,59] */
    int tm_min; /* minutes after the hour - [0,59] */
    int tm_hour;    /* hours since midnight - [0,23] */
    int tm_mday;    /* day of the month - [1,31] */
    int tm_mon; /* months since January - [0,11] */
    int tm_year;    /* years since 1900 */
    int tm_wday;    /* days since Sunday - [0,6] */
    int tm_yday;    /* days since January 1 - [0,365] */
    int tm_isdst;   /* daylight savings time flag */
    };
#define _TM_DEFINED
#endif


/* Clock ticks macro - ANSI version */

#define CLOCKS_PER_SEC  1000


/* Extern declarations for the global variables used by the ctime family of
 * routines.
 */

#ifdef  _NTSDK

#ifdef  _DLL

/* Declarations and definitions compatible with the NT SDK */

#define _daylight   (*_daylight_dll)
#define _timezone   (*_timezone_dll)

/* non-zero if daylight savings time is used */
extern int * _daylight_dll;

/* difference in seconds between GMT and local time */
extern long * _timezone_dll;

/* standard/daylight savings time zone names */
extern char ** _tzname;

#else   /* ndef _DLL */


#ifdef  _POSIX_
extern char * _rule;
#endif  /* _POSIX_ */

/* non-zero if daylight savings time is used */
extern int _daylight;

/* difference in seconds between GMT and local time */
extern long _timezone;

/* standard/daylight savings time zone names */
#ifdef  _POSIX_
extern char * tzname[2];
#else   /* ndef _POSIX_ */
extern char * _tzname[2];
#endif  /* _POSIX_ */

#endif  /* _DLL */

#else   /* ndef _NTSDK */

/* Current declarations and definitions */

#if defined(_DLL) && defined(_M_IX86)

#define _daylight   (*__p__daylight())
_CRTIMP int * __cdecl __p__daylight(void);

#define _timezone   (*__p__timezone())
_CRTIMP long * __cdecl __p__timezone(void);

#define _tzname     (__p__tzname())
_CRTIMP char ** __cdecl __p__tzname(void);

#else   /* !(defined(_DLL) && defined(_M_IX86)) */

/* non-zero if daylight savings time is used */
_CRTIMP extern int _daylight;

/* difference in seconds between GMT and local time */
_CRTIMP extern long _timezone;

/* standard/daylight savings time zone names */
_CRTIMP extern char * _tzname[2];

#endif  /* defined(_DLL) && defined(_M_IX86) */

#endif  /* _NTSDK */


/* Function prototypes */

_CRTIMP char * __cdecl asctime(const struct tm *);
_CRTIMP char * __cdecl ctime(const time_t *);
_CRTIMP clock_t __cdecl clock(void);

/*
_CRTIMP double __cdecl difftime(time_t, time_t);
*/

_CRTIMP struct tm * __cdecl gmtime(const time_t *);
_CRTIMP struct tm * __cdecl localtime(const time_t *);
_CRTIMP time_t __cdecl mktime(struct tm *);
_CRTIMP size_t __cdecl strftime(char *, size_t, const char *,
    const struct tm *);
_CRTIMP char * __cdecl _strdate(char *);
_CRTIMP char * __cdecl _strtime(char *);
_CRTIMP time_t __cdecl time(time_t *);

#ifdef  _POSIX_
_CRTIMP void __cdecl tzset(void);
#else
_CRTIMP void __cdecl _tzset(void);
#endif

/* --------- The following functions are OBSOLETE --------- */
/* The Win32 API GetLocalTime and SetLocalTime should be used instead. */
unsigned __cdecl _getsystime(struct tm *);
unsigned __cdecl _setsystime(struct tm *, unsigned);
/* --------- The preceding functions are OBSOLETE --------- */


#ifndef _SIZE_T_DEFINED
typedef unsigned int size_t;
#define _SIZE_T_DEFINED
#endif

#ifndef _WTIME_DEFINED

/* wide function prototypes, also declared in wchar.h */

_CRTIMP wchar_t * __cdecl _wasctime(const struct tm *);
_CRTIMP wchar_t * __cdecl _wctime(const time_t *);
_CRTIMP size_t __cdecl wcsftime(wchar_t *, size_t, const char *,
    const struct tm *);
_CRTIMP wchar_t * __cdecl _wstrdate(wchar_t *);
_CRTIMP wchar_t * __cdecl _wstrtime(wchar_t *);

#define _WTIME_DEFINED
#endif


#if !__STDC__ || defined(_POSIX_)

/* Non-ANSI names for compatibility */

#define CLK_TCK  CLOCKS_PER_SEC

#ifdef  _NTSDK

/* Declarations and definitions compatible with the NT SDK */

#define daylight _daylight
/* timezone cannot be #defined to _timezone because of <sys/timeb.h> */

#ifndef _POSIX_
#define tzname  _tzname
#define tzset   _tzset
#endif /* _POSIX_ */

#else   /* ndef _NTSDK */

/* Current declarations */

_CRTIMP extern int daylight;
_CRTIMP extern long timezone;
_CRTIMP extern char * tzname[2];

_CRTIMP void __cdecl tzset(void);

#endif  /* _NTSDK */

#endif  /* __STDC__ */


#ifdef __cplusplus
}
#endif


#endif  /* _INC_TIME */

如何在C程序中成功获取当前日期和时间？预先谢谢你。

我正在使用Windows Mobile 5.0 SDK为Motorola MC-55A PDA编写WIN32 C程序。我正在尝试获取当前日期和时间。我尝试使用time_t，但收到链接器错误：“无法解析...

Answer 1

time()函数位于C运行时库中。您可以尝试在编译器选项中添加/MD或/MDd，以添加C运行时库的引用。